It is suggested that neuroticism impairs cognitive performance mostly in difficult tasks i.e. WM tasks, but not so much in easier tasks. However, behavioural, and functional neuroanatomical correlates of detrimental effect of neuroticism in relation to central executive system (CES) during cognitive tasks particularly in multitasking still unknown. I aim at investigating behavioural and functional neuroanatomical correlates of single- and dual-task performance in high and low neurotics. The general hypothesis is that high neurotics will show a poorer performance on processing of cognitive tasks as compared to low neurotics. From a screened population, I select low neurotics (below 6) and high neurotics (over 16) on 24 item Eysenck Personality Questionnaire (EPQ) neuroticism scale. First empirical study was consisted of three standard WM tests. The result of this study showed that high neurotics had lower performance when the task heavily requires CES such as switching and inhibition. Next empirical studies were consisted of dual tasks based on PRP paradigm. In dual task studies, in addition to SOA manipulation SOA (0 and1000ms), task demand manipulated either by presentation of task order or task set maintenance. The results show that high neurotics considerably slower when SOA is short. Further, it has been observed dual task cost differences between high and low neurotics increase as the demand increase either by random tasks or task set maintenance as evident by lower processing efficiency in high neurotics. Also, high neurotics perceived higher stress level as the task demand increase. In the final study, I assessed brain activity by means of functional magnetic resonance imaging (fMRI) in low and high neurotics while they were performing a demanding dual-task and the less demanding component tasks as single-tasks. Imaging data showed that high neurotics showed less dual-task specific activation in lateral and medial prefrontal cortices. In conclusion, I conclude that high levels of neuroticism impair behavioural performance in demanding tasks with higher perceived stress level, and that this impairment is accompanied by reduced activation of the task-associated brain areas. Key words: Neuroticism, Personality, Multitasking, dual-task performance, prefrontal cortex attentional control theory, working memory.

abstract: Humans are capable of transferring learning for anticipatory control of dexterous object manipulation despite changes in degrees-of-freedom (DoF), i.e., switching from lifting an object with two fingers to lifting the same object with three fingers. However, the role that tactile information plays in this transfer of learning is unknown. In this study, subjects lifted an L-shaped object with two fingers (2-DoF), and then lifted the object with three fingers (3-DoF). The subjects were divided into two groups--one group performed the task wearing a glove (to reduce tactile sensibility) upon the switch to 3-DoF (glove group), while the other group did not wear the glove (control group). Compensatory moment (torque) was used as a measure to determine how well the subject could minimize the tilt of the object following the switch from 2-DoF to 3-DoF. Upon the switch to 3-DoF, subjects wearing the glove generated a compensatory moment (Mcom) that had a significantly higher error than the average of the last five trials at the end of the 3-DoF block (p = 0.012), while the control subjects did not demonstrate a significant difference in Mcom. Additional effects of the reduction in tactile sensibility were: (1) the grip force for the group of subjects wearing the glove was significantly higher in the 3-DoF trials compared to the 2-DoF trials (p = 0.014), while the grip force of the control subjects was not significantly different; (2) the difference in centers of pressure between the thumb and fingers (ΔCoP) significantly increased in the 3-DoF block for the group of subjects wearing the glove, while the ΔCoP of the control subjects was not significantly different; (3) lastly, the control subjects demonstrated a greater increase in lift force than the group of subjects wearing the glove (though results were not significant). Combined together, these results suggest different force modulation strategies are used depending on the amount of tactile feedback that is available to the subject. Therefore, reduction of tactile sensibility has important effects on subjects' ability to transfer learned manipulation across different DoF contexts. / Dissertation/Thesis / M.S. Bioengineering 2014

Submitted by Renata Lopes (renatasil82@gmail.com) on 2016-06-01T12:14:13Z No. of bitstreams: 1 andreaolimpiodeoliveira.pdf: 682962 bytes, checksum: 05ece59e8bc4ac8687010ba615a813dc (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2016-07-02T12:55:53Z (GMT) No. of bitstreams: 1 andreaolimpiodeoliveira.pdf: 682962 bytes, checksum: 05ece59e8bc4ac8687010ba615a813dc (MD5) / Made available in DSpace on 2016-07-02T12:55:53Z (GMT). No. of bitstreams: 1 andreaolimpiodeoliveira.pdf: 682962 bytes, checksum: 05ece59e8bc4ac8687010ba615a813dc (MD5) Previous issue date: 2012-02-28 / O presente estudo tem como objetivo investigar o conceito de percepção na Filosofia e Neurociência. Para tanto, descrevemos alguns aspectos históricos da neurociência cognitiva sobre as funções psicológicas superiores, bem como ressaltamos a importância do estudo da percepção no desenvolvimento humano e processos sócio-educativos. Na Filosofia, duas grandes concepções sobre a sensação e a percepção fazem parte da tradição filosófica: o Empirismo e o Racionalismo. No século XX, contudo, a Filosofia alterou bastante essas duas tradições através de uma nova concepção do conhecimento sensível. As mudanças foram trazidas pela Fenomenologia e pela Psicologia da Forma ou teoria da Gestalt. A percepção apresenta estreita ligação com os sentidos, sendo as primeiras etapas realizadas pelos sistemas sensoriais, responsáveis por sua fase analítica. É como se cada característica fosse separada em suas partes constituintes, tais como forma, cor, movimentos e assim por diante. Porém, percebemos o mundo com totalidades integradas e não com sensações fracionadas, o que faz supor que existam outros mecanismos, além daqueles de natureza analítica, que contribuem para nossa percepção sintética. Faz-se necessário entender como a percepção, conceito estritamente subjetivo, se relaciona com o cérebro, abordagem amplamente estudada pela Neurociência Cognitiva. Finalmente, destacamos a importante investigação acerca da percepção realizada pelo neurocientista contemporâneo, Joaquin Fuster, demonstrando como William James, no final do século XIX, já havia escrito de forma muito semelhante. / The present study aims to investigate the concept of perception in Philosophy and Neuroscience. For this, we describe some historical aspects of cognitive neuroscience on the higher psychological functions, as well as emphasize the importance of perception in the study of human development and the socio-educational. In Philosophy, two large conceptions of sensation and perception are part of the philosophical tradition: Empiricism and Rationalism. In the twentieth century, however, the philosophy changed much these two traditions through a new conception of sensitive knowledge. The changes were brought about by the phenomenology and the psychology of form or Gestalt theory. The perception is closely linked to the senses, being the first steps taken by the sensory systems responsible for its analytical phase. It is as if each is separated into its constituent parts, such as shape, color, movement and so on. However, we perceive the world with uncompromising integrity and not with feelings fractionated, which suggests that there are other mechanisms besides those of analytical nature, which contribute to our synthetic perception. It is necessary to understand how perception, strictly subjective concept, relates to the brain, an approach widely studied by Cognitive Neuroscience. Finally, we highlight the important research on the perception held by contemporary neuroscientist Joaquin Fuster, showing how William James, in the late nineteenth century, had written very similarly.

The default mode network (DMN) consists of a set of interconnected brain regions supporting autobiographical memory, our concept of the self, and the internal monologue. These processes must be maintained at all times and consume the highest amount of the brain’s energy during its baseline state. However, when faced with an active, externally-directed cognitive task, the DMN shows a small, but significant, decrease in activity. The reduction in DMN activity during the performance of an active, externally-directed task compared to a baseline state is termed task-induced deactivation (TID), which is thought to ‘free-up’ resources required to respond to external demands. However, older adults show a reduced level of TID in the DMN. Recently, it has begun to be appreciated that this decrease in TID may be associated with poorer cognitive performance, especially during tasks placing high demands on executive function (EF). Diminished DMN TID has not only been associated with increasing age but also with multiple age-related neurobiological correlates such as accumulating Alzheimer’s disease (AD) pathology and reductions in white matter (WM) connectivity. However, these biological factors—age, WM connectivity reductions and increasing AD pathology—are themselves related. Based on the literature, we hypothesized that declining WM connectivity may represent a common pathway by which both age and AD pathology contribute to diminished DMN TID. Further, we hypothesized that declines in DMN function and WM connectivity would predict poorer in EF. Three experiments were carried out to test these hypotheses. Experiment 1 tested whether WM connectivity predicted the level of DMN TID during a task requiring a high level of EF. Results from 117 adults (ages 25-83) showed that WM connectivity declined with increasing age, and that this decline in WM connectivity was directly associated with reduced DMN TID during the task. Experiment 2 tested whether declines in WM connectivity explained both age-related and AD pathology-related declines in DMN TID. Results from 29 younger adults and 35 older adults showed that declining WM connectivity was associated with increasing age and AD pathology, and that this decline in WM connectivity was a common pathway for diminished DMN TID associated with either aging or AD pathology. Experiment 3 investigated whether measures of WM connectivity and DMN TID at baseline could predict EF measured using clinically-used tests. Results from 29 older adults from Experiment 2 showed that less DMN TID predicted poorer EF at baseline and diminished WM connectivity at baseline predicted a greater decline in EF after 3 years. Further, WM connectivity explained reductions in EF predicted by baseline AD pathology, as well as further reductions in EF not predicted by baseline AD pathology. Together the results of these studies suggest that WM connectivity is a key pathway for age-related and AD pathology-related patterns of diminished DMN TID associated with poorer EF. Further, WM connectivity may represent a potential therapeutic target for interventions attempting to prevent future declines in EF occurring in aging and AD.

While it is known that primitive, low-level visual stimuli such as abrupt visual onsets or luminance changes can bias attentional orienting without willful intent on the part of the observer, comparatively little is known about how attention functions in rich, dynamic, meaningful contexts, such as those that comprise our everyday lives. The primary motivating hypothesis of this investigation is that, given our intrinsic needs as evolved social organisms, as well as our capability for behavioral flexibility, the attention system should be sensitive not only to low-level stimulus features, but also to complex stimuli that provide behaviorally relevant information. Three separate lines of research will be presented, each one providing a unique perspective on this issue. The first examined attentional orienting to socially relevant stimuli, finding that eye gaze serves as particularly potent cue for attentional orienting, driving the cortical orienting network more robustly than non-social stimuli, and resulting in a larger attention-related modulation of the early visual processing of stimuli appearing at attended locations. The second line of inquiry investigated patterns of eye movements while participants viewed naturalistic navigational scenes, revealing a dynamic interplay of orienting to the various behaviorally relevant aspects of the scene. The third set of studies specifically addressed whether, given the relevance of heading information for guiding navigational behavior, there is evidence that attention can be oriented automatically to the heading point in an optic flow field simulating the patterns of visual stimulation that accompany self-motion. Together, the results converge on the conclusion that attention can be oriented automatically in a dynamic, flexible, and continuous manner on the basis of complex visual stimuli that provide behaviorally relevant information. / Arts, Faculty of / Psychology, Department of / Graduate

Previous studies completed with humans have revealed insight into the effects of anxiety on attention tasks such the dot-probe task, but there is little information about such effects on non-human primates. This study aimed to assess whether anxiety or anxious behaviors would impact rhesus macaque performance on a three stimuli paradigm similar to the dot-probe task. Utilizing images of conspecifics (strong threat, mild threat, and neutral), eight monkeys were video recorded completing a task that required them to slide two doors, which held these images, to the side to obtain a treat. We hypothesized that behavioral phenotype (high or low anxiety) would affect attention on this modified dot-probe task. Additionally, we predicted that time spent looking at mildly threatening stimuli would be positively correlated with high levels of anxious behaviors (e.g., scratching, yawning, pacing, self-biting) and cortisol concentrations over a four month period. We also predicted that a higher percentage of the mildly threating stimuli as a first choice would be positively correlated with high levels of anxious behaviors and cortisol concentrations. However, anxious behaviors and cortisol concentrations did not affect performance on this task. Interestingly, a sex difference was found for the mild threat stimuli, with females taking significantly more time to complete the task when presented with the mild stimuli (p = 0.01), and also looking at the mild stimuli longer than males (p = 0.03). These data suggest that males and females interpret ambiguous facial expressions differently, possibly indicating the significance of attention in female dominance hierarchies in macaque social groups.

Long term cognitive studies in humans and nonhuman primates such as macaques are difficult because of their long lifespan. The common marmoset (Callithrix jacchus) is a non-human primate who shares with humans many features characteristic of primates, including a complex brain and cognitive function. They also have a short lifespan (~10 years) that makes them a great model in studies of cognitive aging. This study focuses on the rate of decline in cognitive function in male and female marmosets based on performance on reversal learning tasks over 2 years of testing. We found that marmosets improved their overall performance from Year 1 to Year 2 due to practice effect, but that females exhibited an impairment in reversal learning compared to males in both years. We also found important individual differences, with some monkeys showing decline in Year 2 compared to Year 1 while most monkeys maintained or improved their performance in reversal learning over the two years. We conclude that (1) cognitive flexibility, as assessed by reversal learning, is impaired in middle-aged female marmosets compared to males, likely due to sex differences in habitual vs. goal-directed behavior, and (2) that reversal learning is a sensitive measure that can capture one year individual changes in cognitive function.

This study examined the relationships between motivation and cognitive performance in male and female common marmosets (Callithrix jacchus). This question was driven by prior data from the Lacreuse lab showing a robust female impairment in reversal learning, as assessed by the number of trials needed to acquire a reversal following a simple discrimination between two stimuli. This thesis tested the hypothesis that the female impairment in reversal learning was mediated by deficits in motivation. Two sets of measures were used to test this hypothesis. I evaluated physical effort via testing on the progressive ratio (PR), a test that requires animals to produce an increasing number of responses to get a reward. Cognitive effort was evaluated through the number of refusals (aborted trials) produced during performance of a reversal. Because estrogen replacement was previously shown to impair reversal learning in ovariectomized females, I also examined whether PR performance was affected by estrogen levels in a subset of female subjects. Contrary to my hypothesis, reversal learning was not significantly associated with cognitive or physical effort in either males or females. Estrogen levels did not significantly affect physical effort, but there was too much variability in a small sample of females for these results to be compelling. We conclude that the sex difference in reversal learning performance is unlikely to be mediated by sex differences in motivation. Instead females may be more likely than males to engage in habitual processes implicating the dorsal striatum, likely through the action of estrogens on this brain region.

No description available.

The feeling of owning a body part is often investigated by conducting and manipulating the rubber hand illusion, a three-way integration of vision, touch, and proprioception. In the last decade, more research on the role of interoception, the sense of the body's’ internal state, in the illusion has been made. One of the studied factors has been the affective touch, a caress-like, gentle, touch that is performed at a slow specific speed (1-10 cm/sec). Affective touch activates the C tactile afferents which send interoceptive signals to the brain, specifically the insula. The present systematic review investigated the role affective touch has on the strength of the rubber hand illusion. A range of electronic databases was searched for papers reporting research findings published in English before March 20, 2020. Twelve different articles were identified, but only five papers met the inclusion criteria. This thesis looked at the results from these five different studies and compared the effect of affective touch and discriminative, regular, touch have on the rubber hand illusion to see whether there is a significant difference. The results could not show a main effect of stroking velocity, site of stimulation, or social touch, which are components of affective touch. The results was based on four different measurements, the subjective experience of the illusion, pleasantness ratings, proprioceptive drift, and temperature difference in the skin. Opposed what was hypothesized, it could not be demonstrated that affective touch would induce a stronger rubber hand illusion than discriminative touch.